1. Field of the Invention
The present invention relates to the field of computer-aided design. More particularly, the present invention relates to editing computer generated sheetmetal part models and providing the ability to undo and/or redo all previously executed editing operations.
2. Description of the Related Art
Traditionally, editing of sheetmetal part models is performed in two dimensions using orthographic views of the part by drawing lines one by one to create or modify a model. For example, with reference to FIG. 1 eight steps (a-h) required to add a flange to a face of a part model are shown. The editing is performed by drawing one line at a time and ensuring the connectivity of the lines at each step.
In some cases, it is possible to view the editing of entities (e.g., lines, end points, and arcs) in three dimensions (3D). Most existing 3D editing methods, however, are non-intuitive. For example, SPI of Ahrensburg, Germany, has developed sheetmetal packages that can be added on to standard computer-aided design (CAD) systems such as AutoCAD from Autodesk of San Rafael, Calif. and SolidWorks99 from SolidWorks of Concord Mass. These add-on systems transform standard CAD drawings into sheetmetal drawings and enable a user to parametrically edit the sheetmetal part models. Such a system, however, suffers from the drawback that the user cannot see the modifications as they are occurring. Furthermore, such a system is non-intuitive. Thus, a need exists for a system that allows editing of two dimensional and three dimensional sheetmetal part models while allowing the user to view the modifications in real time.
According to the present invention, a method is provided for graphically editing a computer generated sheet metal part model. The method includes displaying the sheet metal part model on a computer display screen, selecting an entity of the sheet metal part model to edit, and selecting an editing operation to be performed on the selected entity. The method also includes performing the selected editing operation on the selected entity, modifying the sheet metal part model in accordance with the performed editing operation, and displaying the modified sheet metal part model on the computer display screen. Consequently, a user views modifications of the sheet metal part model in real time.
According to a preferred embodiment, performing the selected editing operation is accomplsihed by moving a cursor shown on the computer display screen. In addition, a snapping feature is provided to snap an entity to a selected snap point by either angle or length.
In one embodiment, the sheet metal part model is displayed three dimensionally. Alternativley, the sheet metal part model is displayed two dimensionally.
Preferable editing operations are changing existing geometry and creating new geometry. Changing existing geometry can include either breaking the selected entity, moving the selected entity, or stretching the selected entity. Creating new geometry can include either creating a new entity or creating a new corner.
According to a preferred embodiment, an operation manager object is provided for each sheet metal part model. The operation manager object includes a list of every editing operation performed on the part and points to the most recently performed editing operation. Further, each newly created and executed editing operation has an ID that is added to the list after successful execution of the editing operation.
An undo feature may be provided to undo previous editing operations. The undo feature replaces a new entity of a sheet metal part model, which is assigned a unique ID number when the new entity is created by the previous editing operation, with an old entity. Subsequently, the undo feature deletes the new entity from the sheet metal part model.
According to another aspect of the present invention, a computer program embodied in a computer readable medium is provided. The computer program enables graphical editing of a computer generated sheet metal part model. The computer program includes several systems such as a system that displays the sheet metal part model on a computer display screen, and a system for facilitating selecting an entity of the sheet metal part model to edit. Other systems of the computer program are a system for facilitating selecting an editing operation to be performed on the selected entity and a system that performs the selected editing operation on the selected entity. Additional systems include a system that modifies the sheet metal part model in accordance with the performed editing operation and a system that displays the modified sheet metal part model on the computer display screen. The computer programs allows a user to views modifications of the sheet metal part model in real time.
According to a preferred embodiment, the system performing the selected editing operation includes a system that moves a cursor shown on the computer display screen. Alternatively, the system performing the selected editing operation selects a dimension of the sheet metal part model and modifies that dimension.
In one embodiment, the sheet metal part model is displayed three dimensionally. Alternativley, the sheet metal part model is displayed two dimensionally.
Preferable editing operations are changing existing geometry and creating new geometry. Changing existing geometry can include either breaking the selected entity, moving the selected entity, or stretching the selected entity. Creating new geometry can include either creating a new entity or creating a new corner.
According to a preferred embodiment, an operation manager object for each sheet metal part model is included in the computer program. The operation manager object includes a list of every editing operation performed on the part and points to the most recently performed editing operation. Further, each newly created and executed editing operation has an ID that is added to the list after successful execution of the editing operation.
An undo feature may be provided to undo previous editing operations. The undo feature replaces a new entity of a sheet metal part model, which is assigned a unique ID number when the new entity is created by the previous editing operation, with an old entity. Subsequently, the undo feature deletes the new entity from the sheet metal part model.
According to another aspect of the present invention, a system is provided for graphically editing a computer generated sheet metal part model. The system includes a system that displays the sheet metal part model on a computer display screen;a system that selects an entity of the sheet metal part model to edit; and a system that selects an editing operation to be performed on the selected entity the editing system also includes a system that performs the selected editing operation on the selected entity; a system that modifies the sheet metal part model in accordance with the performed editing operation; and a system that displays the modified sheet metal part model on the computer display screen. Thus, a user views modification of the sheet metal part model in real time.